Commit 1dac0dd7 authored Jan 15, 2013 by Mark Rutland

arm64: arm_generic: prevent reading stale time



Currently arch_counter_get_cnt{p,v}ct can be speculated, allowing for
stale time values to be read. This could be problematic for the delay
loop and other sensitive functions, as the time delta could jump around
unexpectedly.

This patch adds isbs to arch_counter_get_cnt{p,v}ct, preventing this
possibility.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>

parent 8a4da6e3

arch/arm64/include/asm/arm_generic.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -83,6 +83,7 @@ static inline cycle_t arch_counter_get_cntpct(void)
		{
		cycle_t cval;

		isb();
		asm volatile("mrs %0, cntpct_el0" : "=r" (cval));

		return cval;
		@@ -92,6 +93,7 @@ static inline cycle_t arch_counter_get_cntvct(void)
		{
		cycle_t cval;

		isb();
		asm volatile("mrs %0, cntvct_el0" : "=r" (cval));

		return cval;